Methods and apparatus for multicasting content

ABSTRACT

A transmitter device of the content distribution system transmits content portions of a content message to a receiver device using respective multicast channels within a network. In such an arrangement, by using multiple multicast channels for transmission of the content portions forming the content message, the transmitter device limits the ability for an unauthorized user, monitoring a particular multicast channel, to distinguishing the content portions from noise or to retrieve the complete content message from the transmitter device, thereby providing security to the content message. Furthermore, the content distribution system utilizes multicast channels within a network to deliver the content portions to all receiver devices in communication with the network, thereby minimizing the power requirements needed by the transmitter device to deliver the content portions to a receiver device farthest from the transmitter device.

BACKGROUND

In general, content distributor devices (e.g., radio transmitters,cellular wireless transmitters) transmit audio, images, or text, (e.g.,content or content messages) to end user or receiver devices (e.g.,radio receivers, cellular wireless receivers) using a variety ofdistribution mechanisms.

One conventional mechanism for content distribution involves broadcasttransmission of content. In broadcast transmission, such as radio orsatellite broadcast, a single content source transmits content to manyreceivers (one-to-many transmission). Certain broadcast transmissions,such as shared-medium broadcasts or Code-Division Multiple Access (CDMA)transmissions, for example, utilize spread-spectrum techniques inbroadcasting the content. Spread-spectrum is a modulation technique thatuses a pseudo-noise (PN) code sequence to “spread” a signal overmultiple frequencies within a channel for transmission (e.g., broadcast)to a receiver device. For example, a transmission device combines aninput signal with a user-specific pseudo-noise code and transmits thecombined signal to a receiver device. The receiver device locallyproduces a correlated signal by generating the same PN code sequence andsynchronizing its code sequence with that of the received code sequence.The receiver device, therefore, tracks the received encoded signal torecover the input signal.

The spread-spectrum technique provides security to a signal transmittedto a receiver device. For example, the spread-spectrum techniqueprovides antijam capabilities to the transmitted signal. Inspread-spectrum, the transmitter transmits the signal, to a receiverdevice, using several frequencies. In such a transmission, anunauthorized user can have difficulty in distinguishing the signal fromnoise. The spread-spectrum technique, therefore, limits the ability foran unauthorized user to “jam” or inject noise within the transmission.

The spread-spectrum technique, furthermore, provides low probability ofinterception (LPI) capabilities to the transmitted signal. For example,when using the spread-spectrum technique, the transmitter devicetransmits a signal to a receiver device using several frequencies. Insuch a transmission, an unauthorized user can have difficulty inretrieving the complete signal from the transmitter device. The spreadspectrum technique, therefore, minimizes interception of the transmittedsignal.

Another conventional mechanism for content distribution involvesmulticast transmission. In multicast transmission, such as InternetProtocol (IP) multicast or application-level multicast, a content sourcetransmits content to many receivers (e.g., one-to-many) using amulticast-enabled network. For example, assume a content source (e.g.,content server) receives, over a computer network, requests for contentfrom multiple requesting devices (e.g., client devices). The contentsource provides content to the network in response to the contentrequests. In multicast transmission, multicast-enabled datacommunications devices within the network distribute the content to allof the multiple requesting devices. The content source, therefore,provides the requested content to the network once and allows themulticast-enabled data communications devices within the network todistribute the content to the requesting devices. Multicast distributionof content over the network limits loading of a particular contentsource with the task of providing, for multiple iterations, identicalcontent to multiple requesting devices, thereby allows for a moreefficient operation of the content source.

SUMMARY

Conventional techniques for providing content to a user suffer from avariety of deficiencies.

For example, as described above, certain broadcast transmissions utilizespread-spectrum techniques in transmitting a signal (e.g., content) to areceiver to provide security to such signal transmissions. Broadcasttransmission of content, however, has a cost component associated withtransmitting the content to a particular audience. For example, tobroadcast content as a radio frequency (RF) signal, the transmitter ofthe signal must drive the signal with a sufficient amount of power todeliver the signal to the farthest receiver from the transmitter. Thegreater the distance between the receiver and the transmitter, thegreater the amount of power required for transmission of the signal tothe receiver. Such an increase in the power requirement for broadcastingthe signal to a receiver, in turn, increases the cost of the broadcastfor the transmitter of the signal.

Also as indicated above, other conventional mechanisms for contentdistribution involves multicast transmission of content. Certainmulticast-enabled networks provide multicast transmission of content tomultiple receivers. In such conventional networks, a content sourceprovides, at a single instance, content requested by multiple requestingdevices to the network. The multicast-enabled data communicationsdevices within the network then distribute the content to the multiplerequesting devices. Compared to the transmitters in broadcasttransmission, the content source does not experience an increase in costfor transmitting the content requesting devices located at a relativelylarge distance away from the content source. However, content sources,in certain conventional cases, transmit content over multicast-enablednetworks in an unprotected or non-secured manner, thereby allowingunauthorized users to intercept and identify the content. For contentconsidered as privileged or private communication (e.g., businesscommunications), such interception and identification of the content canbe damaging (e.g., financially damaging) to the transmitter or receiver.

In certain cases, conventional transmitters encrypt content prior totransmitting the content to a receiver over a network. Transmitterdevices, however, typically transmit encrypted content over a singlechannel or path within the network. For example, a multicast channelwithin the conventional multicast network includes a number ofmuliticast-enabled data communications devices. These datacommunications devices carry the encrypted information between thecontent server and the requesting device. In such a case, anunauthorized user can monitor a muliticast-enabled data communicationsdevice within the network and intercept, and potentially decrypt, theencrypted content. For encrypted content considered as privileged orprivate communication (e.g., business communications), such interceptionand decryption of the encrypted content can be damaging (e.g.,financially damaging) to the transmitter or receiver.

By contrast, embodiments of the present invention significantly overcomesuch deficiencies and provide techniques for transmitting and receivingcontent in a content distribution system. A transmitter device of thecontent distribution system transmits content portions of a contentmessage to a receiver device using multiple multicast channels within anetwork. The receiver device, in turn, receives the content portionstransmitted over each respective multicast channel in the network andassembles the content portions to form the original content message. Insuch an arrangement, by using multiple multicast channels fortransmission of the content portions forming the content message, thetransmitter device limits the ability for an unauthorized user,monitoring a particular multicast channel, to distinguish the contentportions from noise or to retrieve the complete content message from thetransmitter device, thereby providing security to the content message.Furthermore, the content distribution system utilizes multicast channelswithin a network to deliver the content portions to all receiver devicesin communication with the network, thereby minimizing the powerrequirements needed by the transmitter device to deliver the contentportions to a receiver device farthest from the transmitter device.

In one embodiment of the invention, a transmitter device of a contentdistribution system detects a plurality of multicast channels fortransmission of the content to a receiver device. The transmitter deviceassigns portions of the content to respective multicast channels of theplurality of multicast channels for distribution to the receiver deviceand transmits the portions of the content to the receiver device usingthe respective assigned multicast channels. The use of multiplemulticast channels by the transmitter device allows cost-effectivedelivery of the content to a receiver device at a relatively largedistance from the transmitter device. Furthermore the use of multiplemulticast channels provides security to content transmitted over thecontent distribution system by minimizing the ability for anunauthorized user, monitoring a particular multicast channel, tointercept an entire content message or discern a difference between thecontent portions and noise transmitted over the multicast channels.

In one arrangement, the transmitter device assigns a noise element to atleast one of the multicast channels and transmits the noise elementusing the assigned multicast channel. The noise element providesadditional security to the content portions transmitted via the assignedmulticast channels by minimizing the possibility for an unauthorizeduser, monitoring the multicast channels, to detect a difference betweenthe noise element and the content portions.

In one arrangement, the transmitter device, prior to transmitting thenoise element using the assigned multicast channel, transmits a firstsynchronization marker to the receiver device using the assignedmulticast channel. After completing transmission of the noise elementusing the assigned multicast channel, the transmitter device transmits asecond synchronization marker to the receiver device using the assignedmulticast channel. After the transmitter device transmits the secondsynchronization marker to the receiver device using the assignedmulticast channel, the transmitter device transmits a portion of thecontent to the receiver device using the respective assigned multicastchannel. Use of the synchronization markers allows the receiver deviceto identify and discard the noise elements transmitted by thetransmitter device.

In one arrangement, the transmitter device detects a time durationassociated with a first multicast channel of the plurality of multicastchannels. The transmitter device, when assigning and transmitting,transmits a first portion of the content to the receiver device duringthe time duration using a first multicast channel. The transmitterdevice further detects expiration of the time duration associated withthe first multicast channel, switches to a second multicast channel inresponse to detecting expiration of the time duration, and transmits asecond portion of the content to the receiver device using therespective second multicast channel. The transmitter device and thereceiver device each utilize time duration information (e.g., timeduration) to substantially synchronously transmit or receive contentportions, over each of the multicast channels in a “rolling fashion”(e.g., serial use of each of the multicast channels, one after another).The transmitter device and the receiver device utilize each multicastchannel for a relatively small period of time (e.g., relatively smalltime duration) and, therefore, minimize the possibility for anunauthorized user or attacker to inject unauthorized content (e.g.,noise) into the message or content transmitted to the receiver device.

In one arrangement, the transmitter device prior to transmitting theportions of the content to the receiver device using the respectiveassigned multicast channels, transmits a first authorization value tothe receiver device using the respective assigned multicast channels toindicate a start of transmission from and an identity of the transmitterdevice. After completing transmission of the portions of the content tothe receiver device using the respective assigned multicast channels,the transmitter device transmits a second authorization value to thereceiver device using the respective assigned multicast channels toindicate an end to the transmission from and the identity of thetransmitter device. The authorization values indicate, to the receiverdevice, an identity of the transmitter device and a beginning and anending, respectively, to legitimate communications (e.g., contentportions) carried by the multicast channel. Use of the authorizationvalues limits the ability for an unauthorized user to inject,undetected, unauthorized content or noise into a particular multicastchannel and thereby “jam” the transmission of the content message fromthe transmitter device to the receiver device.

In one arrangement, the transmitter device, when assigning, based upon acontent spreading characteristic, assigns portions of the content to therespective multicast channels of the plurality of multicast channels fordistribution to the receiver device, the content spreadingcharacteristic indicating a division of the content into the respectiveportions of the content. Furthermore, when transmitting, the transmitterdevice substantially simultaneously transmits the portions of thecontent to the receiver device using the respective assigned multicastchannels.

In one arrangement, the transmitter device, when detecting, detects aplurality of multicast channels with each of the plurality of multicastchannels formed along a distinct communication path within the contentdistribution system. In such a case, during transmission of contentportions, not all of the content portions travel through a single datacommunications device. Such an arrangement minimizes the ability for anunauthorized user monitoring a single data communications device withinthe network from intercepting all of the content portions forming acontent message, thereby providing security to transmission of thecontent message via the content distribution system.

In one arrangement, the transmitter device is configured as acomputerized device associated with a content distribution system havingat least one communications interface, a controller (e.g., a memory andprocessor), and an interconnection mechanism coupling the at least onecommunications interface and the controller. The controller isconfigured to detect a plurality of multicast channels for transmissionof the content to a receiver device, assign portions of the content torespective multicast channels of the plurality of multicast channels fordistribution to the receiver device, and transmit the portions of thecontent to the receiver device using the respective assigned multicastchannels.

Other embodiments of the invention include a computer system, such as adata communications device, computerized device, or other deviceconfigured with software and/or circuitry to process and perform all ofthe method operations noted above and disclosed herein as embodiments ofthe invention. In such embodiments, the device, such as a datacommunications device, comprises one or more communications interfaces(e.g., network interfaces), a memory (e.g., any type of computerreadable medium, storage or memory system), a processor and aninterconnection mechanism connecting the communications interface, theprocessor and the memory. In such embodiments, the device encodes thememory system with a content portion transmission application that, whenperformed on the controller, produces a content portion transmissionprocess that causes the computer system to perform any and/or all of themethod embodiments, steps and operations explained herein as embodimentsof the invention. Also, a switch, router or other device programmed orotherwise configured to operate as explained herein is an embodiment ofthe invention.

Other arrangements of embodiments of the invention disclosed hereininclude software programs to perform the method embodiment steps andoperations as summarized above and disclosed in detail below. As anexample, a content portion transmission software control application,such as a data communications device operating system configured tooperate as explained herein is an embodiment of the invention. Moreparticularly, a computer program product is disclosed which has acomputer-readable medium including computer program logic encodedthereon that, when executed on at least one processor or controller,causes the processor or controller to perform the operations (e.g., themethods) indicated herein as embodiments of the invention. Sucharrangements of the invention are typically embodied as software, logicinstructions, code and/or other data (e.g., data structures) arranged orencoded on a computer readable medium such as an optical medium (e.g.,CD-ROM), floppy or hard disk or other medium such as firmware ormicro-code in one or more ROM or RAM or PROM chips or as an ApplicationSpecific Integrated Circuit (ASIC). These software or firmware or othersuch configurations include those installed onto a computer system, datacommunications device or other device to cause such a device to performthe techniques explained herein as embodiments of the invention.

Embodiments of the invention also include computer program products suchas disks, or other readable media that have a computer-readable mediumincluding computer program logic encoded thereon for distributingcontent in a networked computer environment, such that the computerprogram logic, when executed on at least one processing unit with thepresence server, causes the at least one processing unit to perform anyor all of the aforementioned methods.

In one example embodiment, computer software and/or hardware mechanismsimplement the methods embodiments of the invention within a datacommunications device apparatus. It is to be understood that the systemof the invention include those embodied strictly as a software program,as software and hardware, or as hardware alone. The features of theinvention, as explained herein, may be employed in data communicationsdevices and other computerized devices and software systems for suchdevices such as those manufactured by Cisco Systems, Inc. of San Jose,Calif.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features and advantages of theinvention will be apparent from the following description of particularembodiments of the invention, as illustrated in the accompanyingdrawings in which like reference characters refer to the same partsthroughout the different views. The drawings are not necessarily toscale, emphasis instead being placed upon illustrating the principles ofthe invention.

FIG. 1 shows a system for distributing content, according to oneembodiment of the invention.

FIG. 2 illustrates a flow chart of a procedure performed by the systemof FIG. 1, according to one embodiment of the invention.

FIG. 3 illustrates the system of FIG. 1, according to one embodiment ofthe invention.

FIG. 4 shows the system of FIG. 1, according to one embodiment of theinvention.

FIG. 5 illustrates the system of FIG. 1, according to one embodiment ofthe invention.

FIG. 6 depicts a computer implementation of a transmitter device,according to one embodiment of the invention.

FIG. 7 depicts a computer implementation of a receiver device, accordingto one embodiment of the invention.

DETAILED DESCRIPTION

Embodiments of the present invention provide techniques for transmittingand receiving content in a content distribution system. A transmitterdevice of the content distribution system transmits content portions ofa content message to a receiver device using multiple multicast channelswithin a network. The receiver device, in turn, receives the contentportions transmitted over each, respective multicast channel in thenetwork and assembles the content portions to form the original contentmessage. In such an arrangement, by using multiple multicast channelsfor transmission of the content portions forming the content message,the transmitter device limits the ability for an unauthorized user,monitoring a particular multicast channel, to distinguishing the contentportions from noise or to retrieve the complete content message from thetransmitter device, thereby providing security to the content message.Furthermore, the content distribution system utilizes multicast channelswithin a network to deliver the content portions to all receiver devicesin communication with the network, thereby minimizing the powerrequirements needed by the transmitter device to deliver the contentportions to a receiver device farthest from the transmitter device.

FIG. 1 shows a content distribution system 20, according to oneembodiment of the invention. The content distribution system 20 includesa transmitter device 32, a network 28, and a receiver device 34.

The transmitter device 32 is a computerized device configured totransmit content 38 (e.g., a content message) to the receiver device 34.For example, the transmitter device 32 is configured as a computer, suchas a personal computer, or as a cellular telephone. In one arrangement,the transmitter device 32 generates the content 38 for transmission tothe receiver device 34. In another arrangement, the transmitter device32 receives the content 38 from a content source external to thetransmitter device 32 and transmits the content 38 to the receiverdevice 34.

The receiver device 34, in one arrangement, is a computerized deviceconfigured to receive content 38 from the transmitter device 32. Forexample, the receiver device 34 is configured as a computer, such as apersonal computer, or as a cellular telephone.

The network 28 allows communication between the transmitter device 32and the receiver device 34. In one arrangement, the network 28 is an adhoc wireless network. In another arrangement, the network 28 is acomputer network, such as the Internet or a local area network (LAN),that includes data communication devices 36 (e.g., routers, switches,etc.) that transmit content portions 40, forming the content message 38,to the receiver device 34. Particular multicast-enabled datacommunication devices 36 (e.g., devices that provide a one-to-manytransmission of content portions 40) group to form multicast channels30. For example, as illustrated in FIG. 1, the network includesmulticast channels 30-1, 30-2, 30-M. Each multicast channel 30-1, 30-2,30-M provides one-to-many (e.g., multicast) transmission of content 38from a single sender (e.g., transmitter device 32) to multiple receiverdevices 34. For convenience, FIG. 1 illustrates the multicast channels30-1, 30-2, 30-M, in communication with a single receiver device 34.

The content 38 carried by the network 28, as transmitted by thetransmitter device 32 and as received by the receiver device 34, isconfigured as text, audio, or video data, for example.

FIG. 2 illustrates a flowchart 50 showing a method for transmittingcontent 38 by the transmitter device 32 of the content distributionsystem 20, according to one embodiment of the invention. The transmitterdevice 32 and the receiver device 34 utilize multiple multicast channels30 within the network 28 to, respectively, transmit and receive contentportions or fragments 40, forming a content message 38, through thenetwork 28. Transmission and reception of the content portions 40 insuch a manner limits the ability for an unauthorized user, monitoring aparticular multicast channel 30, to distinguishing the content portions40 from a noise signal and thereby provides security to non-encryptedcontent 38 carried by the network 28.

In step 52, the transmitter device 32 detects a plurality of multicastchannels 30-1, 30-2, 30-M for transmission of the content 38 to areceiver device 34. For example, in one arrangement, the transmitterdevice 32 receives multicast channel information 44 from externalsource, such as a computerized device 70 storing the multicast channelinformation 44. In one arrangement, the multicast channel information 44includes addresses corresponding to data communications devices 36associated with each multicast channel 30-1, 30-2, 30-M.

In step 54, the transmitter device 32 assigns portions 40-1, 40-2, 40-Nof the content 38 to respective multicast channels 30-1, 30-2, 30-M ofthe plurality of multicast channels 30 for distribution to the receiverdevice 34. For example, in one arrangement, as will be described below,the transmitter device 32 divides the content 38 into content portions40 based upon a content spreading characteristic or spreading code andassigns each content portion 40 to a particular multicast channels 30-1,30-2, 30-M. In another arrangement, as will be described below, thetransmitter device 32 assigns content portions 40 to the multicastchannels 30 based upon a time duration associated with each multicastchannel.

In step 56, the transmitter device 32 transmits the portions 40-1, 40-2,40-N of the content 38 to the receiver device 34 using the respectiveassigned multicast channels 30-1, 30-2, 30-M. The receiver device 34receives each content portion 40-1, 40-2, 40-N via each respectivemulticast channel 30-1, 30-2, 30-M and combines the portions 40-1, 40-2,40-N to form the content message 38.

The use of multiple multicast channels 30, by the content distributionsystem 20, for transmission of the content 38, allows cost-effectivedelivery of the content 38 to a receiver device at a relatively largedistance from the transmitter device. Furthermore the use of multiplemulticast channels 30 provides security to content 38 transmitted overthe network 28. For example, by using multiple multicast channels 30 totransmit a content message 38 to a receiver device 34, the transmitterdevice minimizes the ability for an unauthorized user, monitoring aparticular multicast channel 30, to intercept the entire content message38. For example, assume an unauthorized user monitors a first multicastchannel 30-1 and intercepts the content portion 40-1 transmitted on thefirst multicast channel 30-1. Furthermore, assume the unauthorized userhas a low probability of monitoring all of the multicast channels 30,within the content distribution system 20, used for transmission of allof the content portions 40 that form the content 38. The content portion40-1 forms only a part of the content message 38 as a whole. Theunauthorized user can only intercept a part of the content message 38and, therefore, has a low probability of understanding the entirecontent message 38 as a whole.

Returning to FIG. 1, the transmitter device 32 and the receiver device34 work in conjunction with each other to provide transmission andreception, respectively, of content 38 over the multicast channels 30 ofthe network 28. For example, assume that the transmitter device 32 andthe receiver device 34 are configured to transmit and receive,respectively, confidential content 38 (e.g., content privy to thetransmitter device 32 and the receiver device 34). The transmitterdevice 32 and the receiver device 34, respectively, transmit and receivesuch content 38 using multiple multicast channels 30 of the contentdistribution system 20 to provide secure transmission of the content 38over the network 28.

For example, in one arrangement, the transmitter device 32 and thereceiver device 34 establish a mutual communication link over thenetwork 28, such as by using a handshaking procedure. Duringestablishment of the communication link, either the transmitter device32, the receiver device 34 or both the transmitter device 32 and thereceiver device 34 detect a need to transmit and receive, respectively,the content 38 using the multicast channels 30 of the network 28 (e.g.,the transmitter device 32 and the receiver device 34 detect the content38 as having confidential information). In such an arrangement, afterthe transmitter device 32 and the receiver device 34 establish thecommunication link, the transmitter device 32 and the receiver device 34each transmit a respective request 70-1, 70-2 to a computerized device72 to request multicast channel information 44 that identifies multicastchannels 30 within the network 28 to be used for distribution of content38 (e.g., confidential content) within the content distribution system22. The multicast channel information 44 ensures that the transmitterdevice 32 transmits, and that the receiver device 34 receives, contenton corresponding (e.g., matching) multicast channels 30.

For example, assume the multicast channel information 44 includesinformation setting multicast channels 30-1, 30-2, and 30-3 of thenetwork 28 for delivery of the content 38. The transmitter device 32examines the multicast channel information 44 (e.g., the multicastaddresses within the multicast channel information 44) as detects themulticast channels 30-1, 30-2, and 30-M as transmitting channels for thecontent 38 (e.g., transmission of the content to the receiver device34). Similarly, the receiver device 34 also examines the multicastchannel information 44 (e.g., the multicast addresses within themulticast channel information 44) and detects the multicast channels30-1, 30-2, and 30-M as reception channels for the content 38 (e.g.,reception of the content from the transmitter device 32). Based on suchdetection by the transmitter device 32 and the receiver device 34, themulticast channel information 44 configures the transmitter device 32 totransmit the content 38 over the multicast channels 30-1, 30-2, and 30-Mand configures the receiver device 34 to receive the content 38 over therespective multicast channels 30-1, 30-2, and 30-M.

In one arrangement, the multicast channel information 44 includesaddresses, such as Internet Protocol (IP) addresses, corresponding toeach multicast group or channel 30-1, 30-2, and 30-M. In anotherarrangement, the multicast channel information 44 includes addresses,such as Internet Protocol (IP) addresses, of a data communicationsdevice 36 corresponding to an associated multicast channel 30-1, 30-2,and 30-M. For example, the multicast channel information 44 indicates,to the transmitter device 32, the IP address of data communicationsdevice 36-1 for the first multicast channel 30-1, the IP address of datacommunications device 36-2 for the second multicast channel 30-2 and thedata communications device 36-3 for the third multicast channel 30-M(e.g., secure data communications devices “near” the transmitter device32). The multicast channel information 44 also indicates, to thereceiver device 34, the IP address of data communications device 36-4for the first multicast channel 30-1, the IP address of datacommunications device 36-5 for the second multicast channel 30-2 and thedata communications device 36-X for the third multicast channel 30-M(e.g., secure data communications devices “near” the receiver device34). In such an arrangement, the content distribution system forms eachof the multicast channels 30 along distinct communication paths (e.g.,creates path diversity) within the network 28 of the contentdistribution system 20. In such an arrangement, during operation, thetransmitter device 32 transmits, and the receiver device 34 receives,the content portions 40 forming the content message 38 via distinct datacommunications devices 36 within the network 28. Because not all of thecontent portions 40 travel through a single data communications device,such an arrangement minimizes the ability for an unauthorized usermonitoring a single data communications device 36 within the network 28from intercepting all of the content portions 40 forming the contentmessage 38.

As indicated above, after detecting the multicast channels 30-1, 30-2,and 30-M for transmission of the content 28 to the receiver device 34,the transmitter device 32 assigns content portions or content portions40 of the content message 38 to the respective multicast channels 30-1,30-2, and 30-M. During the assignment, the transmitter device 32 splitsor breaks the content 38 into content portions 40-1, 40-2, 40-N. Forexample, assume the content 38 is a text message. The transmitter device32 divides the text message into content portions 40, or textcomponents, such that each component includes an arbitrary number ofbits or bytes forming the text message. After the transmitter device 32splits the content into content portions 40-1, 40-2, 40-N, thetransmitter device assigns the content portions 40-1, 40-2, 40-N toparticular (e.g., corresponding) multicast channels 30-1, 30-2, 30-M.The transmitter device 32, in one arrangement, utilizes particularmechanisms to break the content 38 into particular content portions 40and assign the content portions 40 to the respective multicast channels30, as described in detail below.

After detecting the multicast channels 30-1, 30-2, and 30-M forreception of the content 38 from the transmitter device 32, the receiverdevice 34 also assigns multicast channels 30 for reception of contentportions 40-1, 40-2, 40-N of the content 38 from the transmitter device32. For example, in one arrangement, when assigning the multicastchannels 30 the receiver device 34 monitors the multicast channels 30-1,30-2, and 30-M within the network 28, based upon the multicast channelinformation 44.

When the transmitter device 32 transmits the portions 40-1, 40-2, 40-Nof the content 38 to the receiver device 34 using the respectiveassigned multicast channels 30-1, 30-2, 30-M, the receiver device 34, inturn receives the portions 40-1, 40-2, 40-N of the content 38 using therespective assigned multicast channels 30-1, 30-2, 30-M. For example, asthe transmitter device 32 transmits the first content portion 40-1 usingthe first multicast channel 30-1, the receiver device 34, monitoring thefirst multicast channel 30-1, receives the first content portion 40-1over the first multicast channel 30-1. Thereafter, as the transmitterdevice 32 transmits the second content portion 40-2 and the thirdcontent portion 40-N using the second multicast channel 30-2 and thethird multicast channel 30-M, respectively, the receiver device 34,monitoring the second multicast channel 30-2 and the third multicastchannel 30-M, receives the second content portion 40-2 and the thirdcontent portion 40-N. In such an arrangement, transmission and receptionof portions 40 of the content 38 using multiple multicast channels 30within a network 28 provides security in to the content message 38, as awhole, transmitted over the network 28.

The use of multiple multicast channels 30 within a network 28 providessecurity to the content messages 38 transmitted from a transmitterdevice 32 to a receiver device 34. The use of multiple multicastchannels 30 for transmission of content 38 limits the ability for anunauthorized user, monitoring a particular multicast channel 30, toeither distinguish content portions 40 of a content message 38 fromnoise on the multicast channel 30 or retrieve the complete contentmessage 38 from the transmitter device 32. In one arrangement, thecontent distribution system 20 provides additional security safeguardsto the content 38 transmitted over the network 28 via the multicastchannels 30.

FIG. 3 illustrates an arrangement of the content distribution system 20where the transmitter device 32 assigns a noise element 64 to amulticast channel 30-2 and transmits the noise element 64 over anassigned multicast channel 30-2. In one arrangement the noise element 64is minimally different (e.g., not detectably different) from the contentportions 40-1, 40-2 transmitted over the assigned multicast channel30-2. The noise element 64, therefore, provides additional security tothe content portions 40 transmitted via the assigned multicast channel30-2 by minimizing the possibility for an unauthorized user, monitoringthe multicast channel 30-2, to detect a difference between the noiseelement 64 and the content portions 40-1, 40-2.

For example, assume that the content 38 to be transmitted using themulticast channel 30-2 is the text message “cars, trucks, and buses” andthat the transmitter device 32 splits the content 38 into contentportions 40-1, 40-2, 40-N such that the first content portion 40-1contains the text string “cars,”, the second content portion 40-2contains the text string “trucks,”, and the third content portion 40-Ncontains the text string “and buses”. Next, assume the transmitterdevice 32 transmits the content portions 40-1, 40-2, 40-N over themulticast channels 30-1, 30-2, 30-M along with noise elements 64 wherethe noise elements 64 are similar to the content portions 40 (e.g.,configured as the same data type as the content portions 40). Forexample, using the first multicast channel 30-1, the transmitter device32 transmits the first content portion 40-1 “cars,” and then transmits afirst noise element 64 “airplanes, “and a second noise element 64 “andtanks,”. Using the second multicast channel 30-2, the transmitter devicetransmits a first noise element 64 “jeeps,”, the second content portion40-2 “trucks,”, and a second noise element 64” and skis”. Using thethird multicast channel 30-M, the transmitter device transmits a firstnoise element 64 “pigeons,”, a second noise element 64 “pedestrians,”,and the third content portion 40-N “and buses”.

As the transmitter device 32 transmits the content portions 40-1, 40-2,40-N to the receiver device 34, for an unauthorized user monitoring thedata communications carried over the multicast channels 30-1, 30-2,30-M, the unauthorized user receives the content portions 40-1, 40-2,40-N along with the noise elements 64. Because the noise elements 64 areconfigured as the same data type as the content portions 40-1, 40-2,40-N the noise elements 64 hide the nature of the content 38 (e.g.,message) distributed by the transmitter device 32. The use of the noiseelements 64, therefore, minimizes the possibility for the unauthorizeduser to distinguish the noise elements 64 from the content portions40-1, 40-2, 40-M and, therefore, accurately detect a portion of thecontent message 38.

In one arrangement, prior to transmitting the noise element 64, thetransmitter device 32 transmits a first synchronization marker 60 to thereceiver device 32 using the assigned multicast channel 30-1. Aftercompleting transmission of the noise element 64 to the receiver device34, the transmitter device 32 transmits a second synchronization marker62 and a subsequent portion 40-2 of the content 38 to the receiverdevice 32 using the assigned multicast channel 30-1. Use of thesynchronization markers 60, 62 allows the receiver device 34 to identifyand discard the noise elements 64 transmitted by the transmitter device32 (e.g., “synchronizes” the receiver device 34 with the noise elements64 transmitted by the transmitter device 32). For example, when thereceiver device 34 receives the first synchronization marker 60 via theassigned multicast channel 30-1, the receiver device 34 ignores allcommunications (e.g., the noise element 64) received from thetransmitter device 32 until the receiver device 34 receives the secondsynchronization marker 62. Upon reception of the second synchronizationmarker 62 via the assigned multicast channel 30-1, the receiver device34 detects a subsequent content portion 40-2 transmitted by thetransmitter device 32 using the multicast channel 30-1.

In one arrangement, the synchronization markers 60, 62 include flag orstrings configured as the same data type as the content portions 40 andare indistinguishable from the content portions 40 by an unauthorizeduser. Such an arrangement, limits the possibility for an unauthorizeduser to detect the synchronization markers 60, 62 as indicating thepresence of noise elements 64 transmitted over a multicast channel 30.In one arrangement, the transmitter device 32 selects the firstsynchronization marker 60 from a group of synchronization markers usedto indicate the beginning of transmission of a noise element 64 andselects the second synchronization marker 62 from a group ofsynchronization markers used to indicate the end of transmission of anoise element 64. In such an arrangement, the transmitter device varies,over time, the synchronization markers 60, 62 transmitted to thereceiver device 34, thereby limiting the possibility for an unauthorizeduser to distinguish particular portions, transmitted over the multicastchannels 30, as synchronization markers 60, 62.

As indicated above, the use of multiple multicast channels 30 fortransmission of content portions 40 forming content 38 minimizes therisk of an unauthorized user intercepting all of the content portions 40forming the content 38 and, thereby, intercept the content 38 (e.g.content message) as a whole. The content distribution system 20 providesvarious mechanisms for dividing the content message 28 into contentportions 40 and distributing the content portions 40 using the multiplemulticast channels 30, as described below.

FIG. 4 illustrates one arrangement of the content distribution system 20where the transmitter device 32 transmits, and the receiver device 34receives, content portions 40 using each of the multicast channels 30-1,30-2, and 30-M in a “rolling fashion” (e.g., serial use of each of themulticast channels 30-1, 30-2, and 30-M, one after another). Thetransmitter device 32 and the receiver device 34 switch from the firstmulticast channel 30-1 to the second multicast channel 30-2 and from thesecond multicast channel 30-2 to the third multicast channel 30-2 in asynchronized manner to transmit and receive, respectively, contentportions 40 over each multicast channel 30-1, 30-2, 30-M for arelatively small period of time. Because the transmitter device 32 andthe receiver device 34 utilize each multicast channel 30-1, 30-2, and30-M for a relatively small period of time, such a configurationminimizes the possibility for an unauthorized user or attacker to injectunauthorized content (e.g., noise) into the message or content 38transmitted to the receiver device 34. Transmission and reception ofcontent portions 40 over each of the multicast channels 30-1, 30-2, and30-M, therefore, maintains the integrity of the content message 38 as awhole.

In order for the transmitter device 32 and the receiver device 34 toswitch between multicast channels 30 in a synchronized manner, thetransmitter device 32 and the receiver device 34 each utilize timeduration information 66 to substantially synchronously transmit orreceive content portions 40, over each of the multicast channels 30-1,30-2, and 30-M. The time duration information 66 indicates an amount oftime (e.g., time duration 68) that the transmitter device 32 and thereceiver device 34 use a particular multicast channel 30 fortransmission and reception of content portions 40. The time durationinformation 66 allows for synchronization between the transmitter device32 and the receiver device 34 such that the transmitter device 32 andthe receiver device 34 identify a time to substantially simultaneouslyswitch transmission and reception of the content portions 40 from afirst multicast channel 30-1 to a second multicast channel 30-2.

For example, in one arrangement, the transmitter device 32 and thereceiver device 34 each the time duration information 66 from thecomputerized device 72, as shown in FIG. 1, with the requested multicastchannel information 44. In one arrangement, the time durationinformation 66 includes a shared mechanism or “shared secret” thatcauses the transmitter device 32 and the receiver device 34 to producesynchronized pseudorandom numbers. Each pseudorandom number producedcorresponds to a particular multicast channel address within themulticast channel information 44 and represents an amount of time 68that the transmitter device 32 and the receiver device 34 utilize aassociated multicast channel 30, such as measured by clock devices(e.g., network time server (NTS) clocks or global positioning system(GPS) clocks) associated with each of the transmitter device 32 and thereceiver device 34. The pseudorandom number and multicast addresses,therefore, form a multicast address and time duration pair (e.g.,[multicast address, time duration]) for transmission of content portions40 over the network 28.

During operation, the transmitter device 32 and the receiver device 34detect a time duration, based upon the time duration information 66,associated with a first multicast channel 30-1 of the multicast channels30 within the network for transmission and reception of a contentportion 40 over the multicast channel 30-1. The transmitter device 32transmits a first portion of the content 40-1 to the receiver device 34during the first time duration 68 using the first multicast channel30-1. The receiver device 34, in turn, receives the first portion of thecontent 40-1 to the receiver device 34 during the first time duration 68using the first multicast channel 30-1. The transmitter device 32 andthe receiver device 34 each monitor the first time duration 68 anddetect an expiration of the first time duration 68 associated with thefirst multicast channel 30-1. The transmitter device 32 and the receiverdevice 34 switch to a second multicast channel 30-2 in response todetecting expiration of the first time duration. The transmitter device32 transmits, and the receiver device 34 receives, a second portion ofthe content 40-2 using the respective second multicast channel 30-2.Such a configuration minimizes the possibility for an unauthorized userto inject noise into the content message 38 transmitted to the receiverdevice 34.

For example, assume the time duration information 66 indicates that thetransmitter device 32 and the receiver device 34 transmit and receive,respectively, data over the first multicast channel 30-1 for a firsttime duration of 0.25 seconds and over the second multicast channel fora second time duration of 0.25 seconds. Further assume the content 38for transmission is the text string “Friends, Romans, Countrymen”.During operation, the transmitter device 32 then transmits a contentportion 40-1 of the content 38 to the receiver device 34 using the firstmulticast channel 30-1 for a first time duration 68-1 of 0.25 seconds.The receiver device 34 also receives the content portion 40-1 of thecontent 38 from the transmitter device 32 using the first multicastchannel 30-1 for the first time duration 68-1 of 0.25 seconds. In suchan arrangement, the transmitter device 32 arbitrarily splits orfragments the content 38 into content portions 40.

For example, in the first time duration 68-1 of 0.25 seconds, asillustrated in FIG. 4, the transmitter device 32 transmits, and thereceiver device 34 receives, the text “Frien” as the first contentportion 40-1. Upon expiration of the first time duration 68-1, thetransmitter device 32 and the receiver device 34 switch to the secondmulticast channel 30-2 for respective transmission and reception of thesecond content portion 40-2. For the second time duration 68-2 of 0.25seconds, as illustrated, the transmitter device 32 transmits, and thereceiver device 34 receives, via the second multicast channel 30-2, thetext string “ds, Roma” as the second content portion 40-2. Uponexpiration of the second time duration 68-2, the transmitter device 32and the receiver device 34 switch to the third multicast channel 30-Mfor respective transmission and reception of a third content portion40-2. As illustrated, the transmitter device 32 transmits, and thereceiver device 34 receives, via the third multicast channel 30-M, thetext string “ns, Countrymen” as the third content portion 40-N.

In one arrangement, the transmitter device 32 transmits an authorizationvalue 42 to the receiver device 34 prior to transmitting a contentportion 40 to the receiver device 32. For example, as illustrated inFIG. 1, prior to transmitting the content portion 40-1 via the firstmulticast channel 30-1 within the network 28, the transmitter device 32transmits a first authorization value 42-1 to the receiver device 34using the respective first multicast channel 30-1 (e.g., the respectiveassigned multicast channel 30-1 for content portion 40-1). Aftertransmitting the content portion 40-1 via the first multicast channel30-1, the transmitter device 32 transmits a second authorization value42-2 to the receiver device 34. The first authorization value 42-1 andthe second authorization value 42-2 indicate, to the receiver device 34,an identity of the transmitter device 32 and a start and end oftransmission from the transmitter device 32, respectively (e.g., thestart and end of “legitimate communications” or content portions 40 ofthe content message 38) carried by the multicast channel 30.

In one arrangement, the transmitter device 32 and the receiver device 34generate or derive the authorization values 42-1, 42-2 based upon theshared mechanism or “shared secret” received form the computerizeddevice 72 and utilizing an algorithm common to both the transmitterdevice 32 and the receiver device 34. The use of the authorizationvalues 42-1, 42-2 limits the ability for an unauthorized user to injectunauthorized content or noise into a particular multicast channel 30 andthereby “jam” the transmission of the content message 38 from thetransmitter device 32 to the receiver device 34. In the case where thereceiver device 34 detects content over a particular multicast channelthat does not include associated authorization values 42-1, 42-2, thereceiver device 34 detects the presence of unauthorized content (e.g.,noise transmitted by an unauthorized user) and discontinues reception oftransmission via that particular multicast channel. The receiver deviceswitches to another multicast channel 30, as indicated by the multicastchannel information 44 to receive further content portions 40 from thetransmitter device 32.

FIG. 5 illustrates another arrangement of the content distributionsystem 20 where the transmitter device 32 transmits, and the receiverdevice 34 receives, content portions 40 using each of the multicastchannels 30-1, 30-2, and 30-M in a “spread spectrum” arrangement. In the“spread spectrum” arrangement, the transmitter device 32 splits thecontent 38 among the multicast channels 30 in the network 28 using acontent spreading characteristic 80. The “spread spectrum” arrangementminimizes the ability for an unauthorized user to intercept and identifyof the content portions 40 forming a content message 38 since there is arelatively low probability that a single unauthorized user knows or hasthe ability to monitor all of the multicast channels 30 used, within thenetwork 28, to transmit the content message 38. Also, the contentspreading characteristic 80 causes the transmitter device 32 todistribute the content 38 as content portion 40 among the multicastchannels 30 such that during transmission, for an unauthorized usermonitoring a single multicast channel, the unauthorized user is unableto distinguish the content portions 40, transmitted over the multicastchannel, from noise.

During operation, the transmitter device 32 and the receiver device 34each receive the content spreading characteristic 80 from thecomputerized device 72, as shown in FIG. 1, with the requested multicastchannel information 44. With respect to the transmitter device 32, thecontent spreading characteristic 80 relates to a mechanism forpartitioning a content message 38 into content portions 40 (e.g.,dividing the content 38 into the respective portions of the content 40)for distribution to the receiver device 34. For example, as shown inFIG. 5, the transmitter device 32, using the content splitting mechanism80, divides the content message 38 (e.g., the text string “Friends,Romans, Countrymen”) into content portions 40-1, 40-2, 40-N where eachcontent portion 40 includes a single character from the text string).The content splitting mechanism 80 also indicated to the transmitterdevice the way in which the transmitter device 32 assigns the contentportions 40-1, 40-2, 40-N to the multicast channels 30. As illustrated,the transmitter device 32 assigns the first content portion “F” 40-1 tothe first multicast channel 30-1, the second content portion “R” 40-2 tothe second multicast channel 30-2 and the third content portion “I” 40-Nto the third content channel 30-M. In the case where the number of bits(e.g. content portions 40) forming the content message 38 is greaterthan the number of available multicast channels 30 in the network 28,the content splitting mechanism 80, in one arrangement, indicates to thetransmitter device 32 to assign the remaining bits forming the contentmessage to each available multicast channel 30 in a round-robin fashion(e.g., a fourth content portion “E” assigned to multicast channel 30-1,a fifth content portion “N” assigned to multicast channel 30-2, a sixthcontent portion “D” assigned to multicast channel 30-M).

After assigning the content portions 40 to the respective multicastchannels 30, the transmitter device substantially simultaneouslytransmits the content portions 40 forming the content 38 to the receiverdevice 34 using the respective assigned multicast channels 30. In turnthe receiver device 34 substantially simultaneously receives the contentportions 40 using the respective assigned multicast channels 30 (e.g.,the assigned multicast channels 30 indicated in the multicast channelinformation 44).

After the receiver device 34 receives the content portions 40 from thetransmitter device 32 via the respective multicast channels 30-1, 30-2,30-M, the receiver device 34 assembles the content portions 40 to formthe content message 38, based upon the content spreading characteristic80. For example, when the receiver device 32 receives the contentportions 40-1, 40-2, 40-N, the receiver device 34 examines the contentportions 40-1, 40-2, 40-N and, based upon the content spreadingcharacteristic 80, detects an order to the content portions 40-1, 40-2,40-N, as divided by the transmitter device 32. Based upon suchdetection, the receiver device 34 assembles the content portions 40-1,40-2, 40-N to form the content message 38 (e.g., the content message 38,prior to division into content portions 40, by the transmitter device32).

FIG. 6 illustrates a more detailed architecture of a transmitter device32 configured according to one embodiment of the invention. FIG. 6 showsa computer device 100, configured to run as a transmitter device 32, inone embodiment of the invention. A computer program product 112 includesan application or logic instructions that are loaded into the computerdevice 100 to configure the device 100 to perform as a transmitterdevice 32. For example, in one arrangement, the transmitter device 32receives the multicast channel information 44 as the computer programproduct 112.

The transmitter device 32, in this example embodiment of the invention,includes an interconnection mechanism 120 such as a data bus and/orother circuitry that interconnects a controller 110, having a memory 116and a processor 118, and one or more communications interfaces 114. Thecommunication interface 114 connects with a receiver device 34 via aconnection 128. For example, the connection 128, in one arrangement is amulticast channel 30 in network 28.

The memory 116 may be any type of volatile or non-volatile memory orstorage system such as computer memory (e.g., random access memory(RAM), read-only memory (ROM), or other electronic memory), disk memory(e.g., hard disk, floppy disk, optical disk and so forth). The memory116 is encoded with logic instructions (e.g., software code) and/or datathat form a content portion transmission application 124 configuredaccording to embodiments of the invention. In other words, the contentportion transmission application 124 represents software code,instructions and/or data that represent or convey the processing logicsteps and operations as explained herein and that reside within memoryor storage or within any computer readable medium accessible to thetransmitter device 32.

The processor 118 represents any type of circuitry or processing devicesuch as a central processing unit, microprocessor orapplication-specific integrated circuit that can access the contentportion transmission application 124 encoded within the memory 116 overthe interconnection mechanism 120 in order to execute, run, interpret,operate or otherwise perform the content portion transmissionapplication 124 logic instructions. Doing so forms the content portiontransmission process 126. In other words, the content portiontransmission process 126 represents one or more portions of the logicinstructions of the content portion transmission application 124 whilebeing executed or otherwise performed on, by, or in the processor 118within the transmitter device 32. The transmitter device 32 in FIG. 1collectively represents either one or both of the content portiontransmission application 124 and the content portion transmissionprocess 126.

FIG. 7 illustrates a more detailed architecture of a receiver device 34configured according to one embodiment of the invention. FIG. 7 shows acomputer device 140, configured to run as a receiver device 34, in oneembodiment of the invention. A computer program product 152 includes anapplication or logic instructions that are loaded into the computerdevice 140 to configure the device 140 to perform as a receiver device34. For example, in one arrangement, the receiver device 34 receives themulticast channel information 44 as the computer program product 152.

The receiver device 34, in this example embodiment of the invention,includes an interconnection mechanism 160 such as a data bus and/orother circuitry that interconnects a controller 150, having a memory 156and a processor 158, and one or more communications interfaces 154. Thecommunication interface 154 connects with a transmitter device 32 via aconnection 128. For example, the connection 128, in one arrangement is amulticast channel 30 in network 28.

The memory 156 may be any type of volatile or non-volatile memory orstorage system such as computer memory (e.g., random access memory(RAM), read-only memory (ROM), or other electronic memory), disk memory(e.g., hard disk, floppy disk, optical disk and so forth). The memory156 is encoded with logic instructions (e.g., software code) and/or datathat form a content portion reception application 164 configuredaccording to embodiments of the invention. In other words, the contentportion reception application 164 represents software code, instructionsand/or data that represent or convey the processing logic steps andoperations as explained herein and that reside within memory or storageor within any computer readable medium accessible to the receiver device34.

The processor 158 represents any type of circuitry or processing devicesuch as a central processing unit, microprocessor orapplication-specific integrated circuit that can access the contentportion reception application 164 encoded within the memory 156 over theinterconnection mechanism 160 in order to execute, run, interpret,operate or otherwise perform the content portion reception application164 logic instructions. Doing so forms the content portion receptionprocess 166. In other words, the content portion reception process 166represents one or more portions of the logic instructions of the contentportion reception application while being executed or otherwiseperformed on, by, or in the processor 158 within the receiver device 34.The receiver device 34 in FIG. 1 collectively represents either one orboth of the content portion reception application 164 and the contentportion reception process 166.

Those skilled in the art will understand that there can be manyvariations made to the embodiments explained above while still achievingthe same objective of those embodiments and the invention in general.

For example, the transmitter device 32 utilizes each multicast channel30 to transmit content portions 40 forming a content message to areceiver device 34. In the case where the transmitter device 32 does notutilize a particular multicast channel 30 for transmission of thecontent portions 40, the transmitter device 32 transmits noise on theunused or non-utilized multicast channels 30.

As indicated above, FIG. 1 illustrates the network 28 as havingmulticast channels 30. The multicast channels 30 provide one-to-manytransmission of content 40 from the transmitter device 32 to thereceiver device 34. In one arrangement, the channels are configured asbroadcast channels that provide broadcast transmission of content fromtransmitter devices 32 to receiver devices 34.

As indicated above, the transmitter device 32 and the receiver device 34transmit requests 70-1, 70-2 for multicast channel information to acomputerized device 72. In one arrangement the transmitter device 32 andthe receiver device 34 transmit the requests 70-1, 70-2 outside of(e.g., not using) the multicast channels 30 of the network 28. Suchnon-multicast channel transmission of the requests 70-1, 70-2 minimizesthe possibility for an unauthorized user, monitoring the multicastchannels 30 of the network 20, to intercept the multicast channelinformation 44 transmitted in response to the respective requests 70-1,70-2 and, therefore, have the ability to access the content portions 40transmitted in the respective multicast channels 30.

As indicated above, in one arrangement, in order for the transmitterdevice 32 and the receiver device 34 to switch between multicastchannels 30 in a synchronized manner, the transmitter device 32 and thereceiver device 34 each utilize time duration information 66 tosubstantially synchronously transmit or receive content portions 40,over each of the multicast channels 30-1, 30-2, and 30-M. The timeduration information 66 indicates an amount of time (e.g., time duration68) that the transmitter device 32 and the receiver device 34 use aparticular multicast channel 30 for transmission and reception ofcontent portions 40. In another arrangement, the time durationinformation 66 relates to a clock formed as part of the content portions40 themselves.

For example, assume the time duration information 68 relates to aparticular number of bits transmitted from the transmitter device 32 tothe receiver device 34. In such a case the time duration information 68indicates to the transmitter device 32 and the receiver device 34 toswitch transmission and reception, respectively, of the content portions40 from a first multicast channel 30-1 to a second multicast channel30-2 after the transmitter device 32 transmits and the receiver device34 receives a particular number of bits (e.g., data pattern) of one ormore content portions 40.

In another example, assume the time duration information 68 is a flagassociated with a content portion 40. In such a case, the transmitterdevice 32 and the receiver device 34 switch transmission and reception,respectively, of the content portions 40 from a first multicast channel30-1 to a second multicast channel 30-2 after the transmitter device 32and the receiver device detect the presence of a time duration flagassociated with a particular content portion 40.

As indicated above, one arrangement of the content distribution system20 involves the transmitter device 32 transmitting, and the receiverdevice 34 receiving, content portions 40 using each of the multicastchannels 30-1, 30-2, and 30-M in a “spread spectrum” arrangement. Insuch a spread spectrum arrangement, during transmission of the contentportions from the transmitter device 32 to the receiver device 34, thecontent portions 40 (e.g., the bits forming the content portions 40) can“collide”. In one arrangement, the transmitter device 32 encodes thecontent portions 40 with an error-detecting or correction code tominimize the effects of a “collision”

In one arrangement of a “collision”, the network 28 drops (e.g., failsto deliver) the collided content portions 40 to the receiver device 34.As the receiver device 34 receives the encoded content portions 40, thereceiver device 34 examines the error-detecting code to detect if thereceiver device has received all of the content portions 40 forming acontent message 38. In the case where, based upon the examination of theerror-detecting code, the receiver device determines that the receiverdevice 34 has not received all of the content portions 40 forming acontent message 38, the receiver device transmits a request to thetransmitter device 32 to re-transmit the content message via themulticast channels 30 of the network 28.

In another arrangement of a “collision”, the transmitter device 32 canselect (e.g., randomly select) a multicast channel 30, for transmissionof content portions 40 to the receiver device 34, already in use byanother device. In such a case, the collision of content portions 40occurs when the receiver device 34 receives, over the multicast channel30, the content portions 40 sent by the transmitter device 32 andreceives content (e.g., information) transmitted by the other deviceusing the same multicast channel 30. As the receiver device 34 receivesthe encoded content portions 40, the receiver device 34 examines theerror-detecting code to distinguish the content portions 40 sent fromthe transmitter device 32 from the information or content received fromthe other device using the multicast channel 30.

As indicated above, the network 28 is a computer network havingmulticast-enabled data communication devices 36 (e.g., devices thatprovide a one-to-many transmission of content portions 40) grouped toform multicast channels 30. As illustrated in FIG. 1, each multicastchannel 30-1, 30-2, 30-M includes distinct data communications devices36 (e.g., multicast channel 30-1 includes devices 36-1 and 36-4,multicast channel 30-2 includes devices 36-2 and 36-5, and multicastchannel 30-M includes devices 36-3 and 36-X). Such an arrangement is byway of example only. In another arrangement, some or all of the datacommunications devices 36 participate in multiple, distinct multicastchannels 30.

For example, assume the data communications device 36-1 forms part ofeach distinct multicast channel 30-1, 30-2, and 30-M. In such a case,when the transmitter device 32 sends a first content portion 40-1 to thereceiver device 34 using the first multicast channel 30-1, the datacommunications device 36-1, acting as part of the first multicastchannel 30-1 can carry (e.g., aid in transmission of) the first contentportion 40-1 to the receiver device 34. When the transmitter device 32sends a second content portion 40-2 to the receiver device 34 using thesecond multicast channel 30-2, the data communications device 36-1,acting as part of the second multicast channel 30-2 can carry the secondcontent portion 40-2 to the receiver device 34. When the transmitterdevice 32 sends a third content portion 40-N to the receiver device 34using the third multicast channel 30-M, the data communications device36-1, acting as part of the third multicast channel 30-M can carry thethird content portion 40-N to the receiver device 34.

As indicated above, as shown in FIG. 5, the transmitter device 32, usingthe content splitting mechanism 80, divides the content 38 (e.g., thetext string “Friends, Romans, Countrymen”) into content portions 40-1,40-2, 40-N where each content portion 40 includes a single characterfrom the text string. Such an arrangement is by way of example only. Inanother arrangement, the transmitter device 32, using the contentsplitting mechanism 80, divides the content 38 into content portions40-1, 40-2, 40-N where each content portion 40 includes a single bit(e.g., 1 or 0) that forms part of the content 38.

Such variations are intended to be covered by the scope of thisinvention. As such, the foregoing description of embodiments of theinvention is not intended to be limiting. Rather, any limitations to theinvention are presented in the following claims.

1. In a transmitter device of a content distribution system, a methodfor transmitting content comprising: detecting a plurality of multicastchannels for transmission of the content to a receiver device; assigningportions of the content to respective multicast channels of theplurality of multicast channels for distribution to the receiver device;and transmitting the portions of the content to the receiver deviceusing the respective assigned multicast channels; assigning a noiseelement to at least one of the multicast channels, the noise elementcontaining data pertaining to data of at least one of the portions ofthe content; and transmitting the noise element using the assignedmulticast channel.
 2. The method of claim 1 further comprising prior totransmitting the noise element using the assigned multicast channel,transmitting a first synchronization marker to the receiver device usingthe assigned multicast channel; and after completing transmission of thenoise element using the assigned multicast channel, transmitting asecond synchronization marker to the receiver device using the assignedmulticast channel.
 3. The method of claim 2 wherein, after transmittinga second synchronization marker to the receiver device using theassigned multicast channel, transmitting the portion of the content tothe receiver device using the respective assigned multicast channel. 4.The method of claim 1 further comprising detecting a time durationassociated with a first multicast channel of the plurality of multicastchannels, wherein the steps of assigning and transmitting comprisetransmitting a first portion of the content to the receiver deviceduring the time duration using a first multicast channel, and furthercomprising: detecting expiration of the time duration associated withthe first multicast channel; switching to a second multicast channel inresponse to detecting expiration of the time duration; and transmittinga second portion of the content to the receiver device using therespective second multicast channel.
 5. The method of claim 1 furthercomprising: prior to transmitting the portions of the content to thereceiver device using the respective assigned multicast channels,transmitting a first authorization value to the receiver device usingthe respective assigned multicast channels to indicate a start oftransmission from and an identity of the transmitter device; and aftercompleting transmission of the portions of the content to the receiverdevice using the respective assigned multicast channels, transmitting asecond authorization value to the receiver device using the respectiveassigned multicast channels to indicate an end to the transmission fromand the identity of the transmitter device.
 6. The method of claim 1wherein: the step of assigning comprises, based upon a content spreadingcharacteristic, assigning portions of the content to the respectivemulticast channels of the plurality of multicast channels fordistribution to the receiver device, the content spreadingcharacteristic indicating a division of the content into the respectiveportions of the content; and the step of transmitting comprisessubstantially simultaneously transmitting the portions of the content tothe receiver device using the respective assigned multicast channels. 7.The method of claim 1 wherein the step of detecting comprises detectinga plurality of multicast channels, each of the plurality of multicastchannels formed along a distinct communication path within the contentdistribution system.
 8. The device as in claim 1, wherein transmittingthe portions of the content and the noise element include: duringtransmission, manifesting an appearance, to a third party, that thenoise element and the portion of the content have a similar relevancewith respect to the content due to the noise element and the portionboth containing data of the similar subject matter.
 9. The device as inclaim 1, wherein assigning the noise element to at least one of themulticast channels, the noise element containing data pertaining to dataof at least one of the portions of the content includes: creating thedata of the noise element to be minimally different than data of atleast one of the portions of content so as to minimize an unauthorizeduser from detecting a difference between the noise element and the atleast one of the portion of content.
 10. A computerized deviceassociated with a content distribution system comprising: at least onecommunications interface; a controller; and an interconnection mechanismcoupling the at least one communications interface and the controller;wherein controller is configured to: detect a plurality of multicastchannels for transmission of the content to a receiver device; assignportions of the content to respective multicast channels of theplurality of multicast channels for distribution to the receiver device;and transmit the portions of the content to the receiver device usingthe respective assigned multicast channels; assign a noise element to atleast one of the multicast channels, the noise element containing datathat pertains to similar subject matter as data of at least one of theportions of the content; and transmit the noise element using theassigned multicast channel.
 11. The computerized device of claim 10wherein the controller is further configured to: prior to transmittingthe noise element using the assigned multicast channel, transmit a firstsynchronization marker to the receiver device using the assignedmulticast channel; and after completing transmission of the noiseelement using the assigned multicast channel, transmit a secondsynchronization marker to the receiver device using the assignedmulticast channel.
 12. The computerized device of claim 11 wherein thecontroller is further configured to, after transmitting a secondsynchronization marker to the receiver device using the assignedmulticast channel, transmit the portion of the content to the receiverdevice using the respective assigned multicast channel.
 13. Thecomputerized device of claim 10 wherein the controller is furtherconfigured to detect a time duration associated with a first multicastchannel of the plurality of multicast channels, wherein, when assigning,the controller is configured to allocate a first portion of the contentfor transmission to the receiver device using the first multicastchannel based upon the time duration wherein, when transmitting, thecontroller is configured to transmit the first portion of the content tothe receiver device during the time duration using the respectiveallocated first multicast channel, and wherein the controller is furtherconfigured to: detect expiration of the time duration associated withthe first multicast channel; switch to a second multicast channel inresponse to detecting expiration of the time duration; and transmit asecond portion of the content to the receiver device using therespective assigned second multicast channel.
 14. The computerizeddevice of claim 10 wherein the controller is further configured to:prior to transmitting the portions of the content to the receiver deviceusing the respective assigned multicast channels, transmit a firstauthorization value to the receiver device using the respective assignedmulticast channels to indicate a start of transmission from and anidentity of the transmitter device; and after completing transmission ofthe portions of the content to the receiver device using the respectiveassigned multicast channels, transmit a second authorization value tothe receiver device using the respective assigned multicast channels toindicate an end to the transmission from and the identity of thetransmitter device.
 15. The computerized device of claim 10 wherein thecontroller is further configured to: when assigning, based upon acontent spreading characteristic, assign portions of the content to therespective multicast channels of the plurality of multicast channels fordistribution to the receiver device, the content spreadingcharacteristic indicating a division of the content into the respectiveportions of the content; and when transmitting, substantiallysimultaneously transmit the portions of the content to the receiverdevice using the respective assigned multicast channels.
 16. Thecomputerized device of claim 10 wherein the controller, when detecting,is configured to detect a plurality of multicast channels, each of theplurality of multicast channels formed along a distinct communicationpath within the content distribution system.
 17. A computer programproduct having a computer-readable medium including computer programlogic encoded thereon that, when performed on a controller in acomputerized device having a coupling to at least one communicationsinterface provides a method for performing the operations of: detectinga plurality of multicast channels for transmission of the content to areceiver device; assigning portions of the content to respectivemulticast channels of the plurality of multicast channels fordistribution to the receiver device; and assigning a noise element to atleast one of the multicast channels, the noise element containing datathat pertains to similar subject matter as data of at least one of theportions of the content; transmitting the portions of the content to thereceiver device using the respective assigned multicast channels; andtransmitting the noise element using the assigned multicast channel. 18.A computerized device comprising: at least one communications interface;a controller; and an interconnection mechanism coupling the at least onecommunications interface and the controller; wherein the computerizeddevice is configured to produce a means for multicasting content, suchmeans including: means for detecting a plurality of multicast channelsfor transmission of the content to a receiver device; means forassigning portions of the content to respective multicast channels ofthe plurality of multicast channels for distribution to the receiverdevice; means for assigning a noise element to at least one of themulticast channels, the noise element containing data that pertains tosimilar subject matter as data of at least one of the portions of thecontent; means for transmitting the portions of the content to thereceiver device using the respective assigned multicast channels; andtransmit the noise element using the assigned multicast channel.
 19. Ina receiver device of a content distribution system, a method forreceiving multicast content comprising: detecting a plurality ofmulticast channels for reception of the content from a transmitterdevice; assigning multicast channels of the plurality of multicastchannels for reception of portions of the content from the transmitterdevice; assigning multicast channels of the plurality of multicastchannels for reception of a noise element, the noise element containingdata that pertains to similar subject matter as data of at least one ofthe portions of the content; and receiving the portions of the contentand the at least one noise element using the respective assignedmulticast channels.
 20. The method of claim 19 further comprisingreceiving a first synchronization marker from the transmitter deviceusing the assigned multicast channel to indicate a start of transmissionof a noise element; discarding the noise element received from thetransmitter device using the assigned multicast channel; and receiving asecond synchronization marker from the transmitter device using theassigned multicast channel to indicate an end of transmission of thenoise element.
 21. The method of claim 19 further comprising detecting atime duration associated with a first multicast channel of the pluralityof multicast channels, wherein the step of receiving comprises receivinga first portion of the content during the time duration using the firstmulticast channel, and further comprising: detecting expiration of thetime duration associated with the first multicast channel; switching toa second multicast channel in response to detecting expiration of thetime duration; and receiving a second portion of the content from thetransmitter device using the second multicast channel.
 22. The method ofclaim 19 further comprising: receiving a first authorization value fromthe transmitter device using the respective assigned multicast channelsto indicate a start of reception of the portions of the content from thetransmitter device and an identity of the transmitter device; andreceiving, after completion of transmission of the portions of thecontent from the transmitter device, a second authorization value fromthe transmitter device using the respective assigned multicast channelsto indicate an end to the reception of the content from the transmitterdevice.
 23. The method of claim 19 wherein: the step of receivingcomprises, based upon a content spreading characteristic, substantiallysimultaneously receiving the portions of the content to the receiverdevice using the respective assigned multicast channels, the contentspreading characteristic indicating a division of the content into therespective portions of the content; and assembling the portions of thecontent into content based upon the content spreading characteristic.24. The method of claim 19 wherein the step of detecting comprisesdetecting a plurality of multicast channels, each of the plurality ofmulticast channels formed along a distinct communication path within thecontent distribution system.
 25. A computerized device associated with acontent distribution system comprising: at least one communicationsinterface; a controller; and an interconnection mechanism coupling theat least one communications interface and the controller; whereincontroller is configured to: detect a plurality of multicast channelsfor reception of the content from a transmitter device; assign multicastchannels of the plurality of multicast channels for reception ofportions of the content and at least one noise element from thetransmitter device, the noise element containing data that pertains tosimilar subject matter as data of at least one of the portions of thecontent; and receive the portions of the content and the at least onenoise element using the respective assigned multicast channels.
 26. Thecomputerized device of claim 25 wherein the controller is furtherconfigured to: receive a first synchronization marker from thetransmitter device using the assigned multicast channel to indicate astart of transmission of a noise element; discard the noise elementreceived from the transmitter device using the assigned multicastchannel; and receive a second synchronization marker from thetransmitter device using the assigned multicast channel to indicate anend of transmission of the noise element.
 27. The computerized device ofclaim 26 wherein the controller is configured to detect a time durationassociated with a first multicast channel of the plurality of multicastchannels, and, when receiving, receive a first portion of the contentduring the time duration using the first multicast channel, thecontroller further configured to: detect expiration of the time durationassociated with the first multicast channel; switch to a secondmulticast channel in response to detecting expiration of the timeduration; and receive a second portion of the content from thetransmitter device using the second multicast channel.
 28. Thecomputerized device of claim 25 wherein the controller is furtherconfigured to: receive a first authorization value from the transmitterdevice using the respective assigned multicast channels to indicate astart of reception of the portions of the content from the transmitterdevice and an identity of the transmitter device; and receive, aftercompletion of transmission of the portions of the content from thetransmitter device, a second authorization value from the transmitterdevice using the respective assigned multicast channels to indicate anend to the reception of the content from the transmitter device.
 29. Thecomputerized device of claim 25 wherein the controller is furtherconfigured to: when receiving, based upon a content spreadingcharacteristic, substantially simultaneously receive the portions of thecontent using the respective assigned multicast channels, the contentspreading characteristic indicating a division of the content into therespective portions of the content; and assemble the portions of thecontent into content based upon the content spreading characteristic.30. The computerized device of claim 25 wherein the controller isfurther configured to, when detecting, detect a plurality of multicastchannels, each of the plurality of multicast channels formed along adistinct communication path within the content distribution system. 31.A computer program product having a computer-readable medium includingcomputer program logic encoded thereon that, when performed on acontroller in a computerized device having a coupling to at least onecommunications interface provides a method for performing the operationsof: detect a plurality of multicast channels for reception of thecontent from a transmitter device; assign multicast channels of theplurality of multicast channels for reception of portions of the contentand at least one noise element from the transmitter device, the noiseelement containing data that pertains to similar subject matter as dataof at least one of the portions of the content; and receive the portionsof the content and the at least one noise element using the respectiveassigned multicast channels.
 32. A computerized device comprising: atleast one communications interface; a controller; and an interconnectionmechanism coupling the at least one communications interface and thecontroller; wherein the computerized device is configured to produce ameans for receiving multicast content, such means including: means fordetecting a plurality of multicast channels for reception of the contentfrom a transmitter device; means for assigning multicast channels of theplurality of multicast channels for reception of portions of the contentand at least one noise element from the transmitter device, the noiseelement containing data that pertains to similar subject matter as dataof at least one of the portions of the content; and means for receivingthe portions of the content and the at least one noise element using therespective assigned multicast channels.